Recently, a number of studies have reported remarkably strong, replicable associations with complex disease, including the complement factor H (CFH) gene in age-related macular degeneration[24], [25], [26] and the transcription factor 7-like-2 (TCF7L2) gene in type 2 diabetes[27], [28], [29]. Here, TCF7L2 is linked to type 2 diabetes mellitus.